My 16.5 hp yard machine rider starts cranking good but won't start with each time you try starting it cranks slower and slower until nothing put new battery spark plug and new gas still does it

. Check for spark--perform standard spark test. Clean battery terminals, cable connections, and grounds. Even new batteries should be charged at 2 amps for several hours, prior to installation. Test all fuses with a test light or multimeter.

. Check for fuel--old fuel can get gummy and then turn hard as a rock. In this case, the carburetor needs to be removed and cleaned.

. Clean or replace air filter. Dirt and grass can choke off any small engine.